The present invention relates to a data communication apparatus and, more particularly, to a data communication apparatus equipped with an oral communication means and improved in processing a connection request coming from another station during communication therewith using the oral communication means.
Among data communication apparatuses such as a facsimile apparatus and a personal computer, there exists a type which has an oral communication means (i.e., a telephone unit) separately from the data (e.g., image information) communication means. In this type of data communication apparatus, it is possible to call an operator at a station to exchange necessary information using the oral communication means in advance of transmission of data, e.g., image information. It is, of course, also possible to only converse by use of the oral communication means irrespective of the necessity of transmitting data.
Recently, a new communication service (hereinafter referred to as "catch phone" service) has been put into practice, in which when a conversation request or a data transmission request is made from another station during communication with one station, and the user is informed of this fact by a sound sent from an exchange.
When the user hears calling tones of the catch phone service sent from the exchange during oral communication, he verbally informs the person under communication that the catch phone call has come in, to hold the communication, and then executes a data receiving operation to receive data from the second station.
However, conventional data communication apparatuses do not have a function of automatically switching the telephone circuit to the previously communicated station to re-start the conversation upon completion of the data reception by an interrupt processing caused by the catch phone call. Accordingly, upon completion of the data reception, the circuit is released, and the user cannot make a conversation with the person at the previously communicated station.
To overcome this problem, various apparatuses and systems have been proposed which are adapted to restore the communication with the previously communicated station after executing communication of the catch phone service or an interrupt processing similar to it.
Japanese Patent Application Laid-Open Nos. Sho. 63-67868 and Sho. 64-86660 respectively disclose a facsimile communication system and a data communication system in which when an interrupt instruction is given by an operator or received from another station during transmission of image information, the current transmission of image information is suspended to execute the instructed interrupt processing, and after completion of the interrupt processing the transmission of image information is resumed automatically.
Further, Japanese Patent Application Laid-Open No. Sho. 64-78575 discloses a facsimile apparatus which is constructed such that if transmission is suspended due to some trouble, the stored telephone number is dialed to transmit the image information stored in an image signal memory unit.
Further, in a facsimile apparatus disclosed in Japanese Patent Application Laid-Open No. Hei. 2-51973, when a connection request (catch phone call) comes in from another station during communication with one station, the current communication is temporarily held. During this temporary holding period, the identification information (telephone number) of the station of the catch phone call is stored, and the communication being held is restored. Upon completion of this communication, the station of the catch phone call is called using the stored telephone number.
However, the prior art techniques disclosed in the above publications have the following problems.
In the above prior art techniques, the communication concerned is not an oral communication between persons, but a data communication between machines such as facsimile apparatuses. In the case of such communication between machines, even if it is held or suspended due to reception of a catch phone call, it is guaranteed that the communication holding or suspension state is maintained by the machine. Accordingly, it is easy to automatically restore the communication with the previously communicated station by executing a proper processing after completion of the interrupt data communication.
On the other hand, when oral communication using an oral communication means, i.e., a telephone unit attached to a data communication apparatus is held due to a data transmission request, it is not guaranteed that the person at the previously communicated station will stand by during the data reception. The person may hang up the handset for some reason, or may stand by as desired during the data reception.
Processings to be executed after completion of the data reception, i.e., after the interruption, are different depending on which of the above two cases applies. For example, if the person at the previously communicated station has hung up the handset, it is necessary to call him again, whereas if he stands by, the circuit is restored simply by a hooking operation.
Further, there is a possibility that the operator at the station will leave the telephone unit in spite of the restoration of the circuit by, e.g., the automatic calling.
Thus, the conventional apparatuses do not fully consider a variety of situations in the communication involving persons, and hence do not take advantage of the catch phone service sufficiently.